Random Topic of The Week: Lunar Halos

This is a "ring around the moon" or lunar halo. Vastly overexposed in this 8 second exposure, in the center of the frame, is the moon.
Halos are caused by sunlight being refracted by cirro-stratus clouds. In the case of this lunar halo, the sunlight was first reflected off the gibbous moon, which was three days past full. Cirro-stratus clouds are thin clouds, very high in the atmosphere, and are composed of ice crystals. They bend light at a 22 degree angle, which creates a solar halo or lunar halo that is 44 degrees in diameter. 


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